[R] Fitting models in a loop
Bill.Venables at csiro.au
Bill.Venables at csiro.au
Tue Aug 1 07:16:05 CEST 2006
Murray,
Here is a general paradigm I tend to use for such problems. It extends
to fairly general model sequences, including different responses, &c
First a couple of tiny, tricky but useful functions:
subst <- function(Command, ...) do.call("substitute", list(Command,
list(...)))
abut <- function(...) ## jam things tightly together
do.call("paste", c(lapply(list(...), as.character), sep = ""))
Name <- function(...) as.name(do.call("abut", list(...)))
Now the gist.
fitCommand <- quote({
MODELi <- lm(y ~ poly(x, degree = i), theData)
print(summary(MODELi))
})
for(i in 1:6) {
thisCommand <- subst(fitCommand, MODELi = Name("model_", i), i =
i)
print(thisCommand) ## only as a check
eval(thisCommand)
}
At this point you should have the results and
objects(pat = "^model_")
should list the fitted model objects, all of which can be updated,
summarised, plotted, &c, because the information on their construction
is all embedded in the call.
Bill.
-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Murray Jorgensen
Sent: Tuesday, 1 August 2006 2:09 PM
To: r-help at stat.math.ethz.ch
Subject: [R] Fitting models in a loop
If I want to display a few polynomial regression fits I can do something
like
for (i in 1:6) {
mod <- lm(y ~ poly(x,i))
print(summary(mod))
}
Suppose that I don't want to over-write the fitted model objects,
though. How do I create a list of blank fitted model objects for later
use in a loop?
Murray Jorgensen
--
Dr Murray Jorgensen http://www.stats.waikato.ac.nz/Staff/maj.html
Department of Statistics, University of Waikato, Hamilton, New Zealand
Email: maj at waikato.ac.nz Fax 7 838 4155
Phone +64 7 838 4773 wk Home +64 7 825 0441 Mobile 021 1395 862
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